The present disclosure relates to a wind turbine. Further, the present disclosure relates to a method for controlling a wind turbine.
Typically, the rotor azimuth position is measured by an incremental encoder that encodes the angle of a low speed shaft. The information from the rotary encoder may be used in typical embodiments to control a pitch angle of the wind rotor blades. In the event that the rotary encoder is not calibrated, for example if a gear box of a wind turbine has been changed without a recalibration of the rotary encoder, the rotor position error may cause an asymmetrical load control and significantly increases the turbine loads. Further, it may decrease the annual energy production of a wind turbine.
Typically, a referencing procedure of a rotary encoder requires the rotor to be stopped in a certain position. Then, a small coupling has to be attached and the encoder pin or the rotary encoder has to be turned until the rotary encoder generates a zero degree pulse or value. Then, the coupling is fixed again. Typically, the rotary encoder is fixed to a low speed shaft of a wind turbine by the coupling. The low speed shaft/rotor-position-encoder coupling is typically difficult to adjust and a potential source of referencing errors.